The prevention of somnolence when driving a vehicle is an important issue of road traffic safety. Different devices and methods are known allowing to prevent the vehicle driver from getting sleepy or closing his eyes. For the treatment of somnolence, one often uses the perturbation of the circadian rhythm of sleep.
It is known that an illuminance of 20 lux with blue light, having a wavelength centered on approximately 470 nm, perturbs the circadian rhythm of sleep. Blue light is thus often used to prevent somnolence when driving (see, for example, J. Taillard et al., “In-Car Nocturnal Blue Light Exposure Improves Motorway Driving: A Randomized Controlled Trial”, PLoS ONE 7(10), 2012).
Anti-somnolence devices using blue light are optoelectronic devices consisting of arrays of blue light emitting diodes. These devices may be arranged within the vehicle in order to illuminate it and thus also the driver while driving. They may also be fixed to the frame of the driver's glasses in front of the glasses in order to irradiate directly into the driver's eyes.
However, such devices suffer from some drawbacks. For example, a device illuminating the entire vehicle cabin may affect the comfort and well-being of the driver himself and passengers. When irradiated directly into the eyes, the driver may be blinded by the blue light. Thus, both solutions may not be appropriate to enhance road traffic safety.
According to the foregoing, there exists a need for an improved ophthalmic system to counteract somnolence of a vehicle driver and that resolves the cited problems.